LZ78 compression

A substitutional compression scheme which works by entering
phrases into a dictionary and then, when a reoccurrence of
that particular phrase is found, outputting the dictionary
index instead of the phrase. Several algorithms are based
on this principle, differing mainly in the manner in which
they manage the dictionary.

The most well-known Lempel-Ziv scheme is Terry Welch's
Lempel-Ziv Welch variant of LZ78.